C++ function call with type pointer, parameter confusion: incomplete type is not allowed

Question

I'm trying to wrap my head around C++. I'm going to just give you tiny pieces to help illustrate the idea without making things to convoluted. Btw, im only implementing these methods, i cannot change the setup or parameters.

I have a class for a dynamic array data structure that holds objects called stocks:

typedef class Stock ArrayType;

class DynamicArray {
    ArrayType** items;
    int numberOfElements;
    ...
}

Here's its constructor. I'm supposed to allocate the array and add one item, then set the number of elements.

DynamicArray::DynamicArray(ArrayType* const item){
    Stock *items = NULL; // ... i guess? pointers to pointers confuse me
    // now im guessing i need to create a actual stock array and point the above pointer to it
    items = new Stock[1]; // ERROR: incomplete type is not allowed? I've tried several things, and cant get rid of the red squiggles
    this->numberOfElements = 1;
}

Answer 1

Okay, there are a few problems. Off the bat, you have to include Stock first. The compiler needs the full definition of Stock before it can compile DynamicArray, because of memory allocation by my guess.

Secondly, you want the items member-value to contain the reference to the array created in the constructor. So instead of defining Stock *items[1] in the constructor, assign the value of the new statement directly to this->items; you can ommit this-> as long as you don't define a variable with the same name in whatever function you're working on.

Finally, you're allocating an array of pointers, so you use this syntax: new ArrayType*[1]

Additionally, just as a coding-practices point, you shouldn't mix the use of typedefs and their original types in the same source. So I'd recommend you use ArrayType throughout or not at all.